ACRIDIIDAE 



289 



Eiley and Packard have given an account ^ of some parts of the 

 post-embryonic development of the Eocky Mountain Locust, which 

 enables us to form a satisfactory conception of the stages of de- 

 velopment of the wings. Tig. 175, A, represents the first instar. 

 the young locust, just emerged from the egg and colourless. Fig. 

 iV-i shows some of the subsequent stages of development of the 

 wings, the upper line of figures giving a profile view of the 

 thoracic segments, and 

 the lower line showing 

 their dorsal aspects ; 1 

 shows the condition of 

 the parts in the second 

 instar, the chief differ- 

 ence from the first instar 

 being the development 

 of colour ; in the third 

 instar there is an evident 

 slight development of 

 the future alar organs, 

 exhibited chiefly in the 

 outgrowth and lobing 

 of the free posterior 

 angles of the meso- and 

 metanota, as shown in 

 Fig. 174, 2. After the 

 third moult there is a 

 great difference ; the in- 

 star then disclosed — 

 the fourth — has under- 

 gone a considerable 

 change in the position ^m- ^'^^■- 

 of the meso- and meta 

 thoraces, which are 



thrust forward under the pronotum ; this has become more enlarged 

 and hood-like (Fig. 174, 3) ; at the same time the wing-rudiments 

 have become free and detached, the metathoracic pair being the 

 larger, and overlapping the other pair. The fifth instar (Fig. 174, 

 4) differs but little from the fourth, except in the larger size of the 

 pronotum and wing-rudiments. The sixth — shown in Fig. 175, B 



Caloptenus spreius. North America. A, 

 Newly hatched, much magnified ; B, adult, natural 

 size. (After Eiley.) 



1 First Ann. Sep. U.S. Ent. Oomm. 1878, p. 279. 



VOL. V 



